A color filter used for a liquid crystal display device (LCD) or an image sensor (CCD, CMOS, or the like) is configured by regularly arranging fine colored patterns of red (R), green (G), and blue (B) in general, and of magenta (M), cyan (C), yellow (Y), and black (K) in some cases on a glass substrate or a wafer. Conventionally, pixels constituting the color filter have been produced by a dyeing method, a printing method, a pigment dispersion method, an electrodeposition method or the like.
In any of these methods, the pixels are sequentially formed for each color. In particular, the pigment dispersion method makes it possible to achieve high pattern precision and a stable producing process. Accordingly, the color filter is produced by this method in most cases.
In the pigment dispersion method, a cured film (colored pixel) formed to have a desirable pattern is obtained generally by coating on a substrate a photosensitive colored composition including a colorant, a polymerizable monomer, and a photopolymerization initiator, performing a pre-baking to form a film, then irradiating the film with ultraviolet rays or the like through a desirable mask to cure the irradiated portion, removing the unirradiated portion by a developing process to form a colored pattern, and further subjecting the resultant object to a thermal process. This method is a method which applies a principle that the irradiation with the ultraviolet rays causes the photopolymerization initiator to generate an activated radical, and the activated radical attacks a polymerizable group such as a (meth)acryloyl group and provokes a polymerization reaction. That is, the activated radical is essential to initiate the polymerization.
In order to obtain an excellent resolution and a proper line width by the pigment dispersion method, various methods such as an adjustment of an amount by which the activated radical is generated, that is, an adjustment of the type and the amount of the photopolymerization initiator and the like have been contrived hitherto. For example, when the line width to be finally obtained is wide, a method has been applied in which the amount of the activated radical is reduced by using an initiator with a low sensitivity, by reducing the amount of the initiator to be used, or the like and thereby the line width is adjusted to be proper.
However, more severe requirements for the width of the product specification have been introduced in recent years. It has been necessary to reduce the variations in the line width, the film thickness, the scattering spectrum, and the like due to the dependency on the exposing illuminance. That is, variation in the pattern shapes to be formed tends to be easily caused when the exposure is performed with a low illuminance as compared with the case of forming a pattern by exposing with a high illuminance, for example. Regarding these problems due to the dependency on the exposing illuminance, the problem which is hard to solve, especially for the color with a high i-ray transmittance, simply by adjusting the type and the amount of the photopolymerization initiator as described above. A method of increasing the amount of the photopolymerization initiator is generally employed in order to improve the dependency on the exposing illuminance. When the amount of the photopolymerization initiator is increased, on the contrary, the line width becomes excessively wide, and the circumferential residue due to the halation in the exposure is easily generated.
As a method for solving the above-mentioned dependency on the exposing illuminance, a technique for improving the resolution of the pattern with the use of antioxidant has been disclosed and reducing the illuminance of the exposure apparatus (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2006-11397). In addition, a technique for reducing the dependency on the exposing illuminance and improving the resolution of the pattern with the use of another type of antioxidant has been proposed (see, for example, JP-A-2003-25524, and JP-A-2003-25525).